Objective: To investigate the correlation between poorly differentiated clusters (PDCs) in colorectal adenocarcinomas with clinicopathological parameters and its clinicopathological significance. Methods: One hundred and eighty-three colorectal adenocarcinomas resected by radical proctocolecomy were collected at Nanjing Hospital(Nanjing First Hospital), Nanjing Medical University, from January to December 2017. There were 122 male and 61 female patients with age ranging from 42 to 89 years (mean of 68 years). Tumor diameter ranged from 2 to 14 cm (mean 4.5 cm). There were 124 colon cancers and 59 rectal cancers. The number and grade of PDCs in the colorectal adenocarcinoma were evaluated by H-E staining. The overall peritumoural inflammatory reaction was also evaluated. The relationship between PDCs and tumor grades and clinicopathological features and overall peritumoural inflammatory reaction of colorectal adenocarcinoma was analyzed. Results: Of 183 cases of colorectal adenocarcinoma, PDCs were seen in 104 cases (56.8%), of which 36 cases (19.7%) were grade 1, 28 cases (15.3%) were grade 2, and 40 cases (21.9%) were grade 3. PDCs were positively correlated with lymph node metastasis, vascular invasion, degree of differentiation, depth of invasion, and pTNM staging(P<0.05). The detection rate of PDCs in colon cancer was higher than that of rectal cancer(P<0.05). PDCs was unrelated to age, gender, tumor size, and degree of overall peritumoural inflammatory reaction (P>0.05). Among clinicopathological parameters, the grade of PDCs was correlated with lymph node metastasis and vascular invasion (higher than those without lymph node metastasis and vascular invasion, P<0.05); There was a positive correlation between the grade of PDCs and age, tumor differentiation and pTNM staging(P<0.05), and no significant difference between the grade of PDCs and gender, tumor size, tumor location, and depth of invasion was seen (P>0.05). There was no correlation between the grade of PDCs and the degree of overall peritumoural inflammatory reaction (P>0.05). Conclusions PDC is a histological feature that predicts the aggressiveness of colorectal adenocarcinoma. Evaluation of PDC grade can better predict the biological behavior of colorectal cancer and more accurately guide the treatment and evaluate prognosis.